Catheters may be inserted into a patient's vasculature and deployed at various locations within the patient for a wide variety of purposes and medical procedures. For example, one type of catheter is used in percutaneous catheter intervention (PCI) for the treatment of a vascular constriction generally known as a stenosis. In this instance, the catheter has a distally mounted balloon that can be placed, in a deflated or collapsed condition, within the stenosis, and then inflated or expanded to dilate the narrowed lumen of a blood vessel. This type of balloon dilation therapy is generally referred to as percutaneous transluminal angioplasty (PTA). When the treatment is more specifically intended for vessels of the heart, the process is known as percutaneous transluminal coronary angioplasty (PTCA). PTCA is utilized to open coronary arteries that have been occluded by a build up of cholesterol fats and atherosclerotic plaque. The balloon at the distal end of the catheter is inflated causing a widening at the site of the stenosis.
Dilation of an occlusion, however, can form flaps, fissures, and dissections, that may result in reclosure of the dilated vessel or even perforations in the vessel wall. Implantation of a stent can provide support for such flaps and dissections and thereby prevent reclosure of the vessel or provide a patch repair for a perforated vessel wall until corrective surgery can be performed. The stent is typically a cylindrically shaped device formed from wire(s) or a metal tube and is intended to act as a permanent prosthesis. The stent is deployed in a body lumen in a radially compressed configuration and is subsequently radially expanded to contact and support a body lumen. The stent can be implanted during an angioplasty procedure by using a balloon catheter having deployed thereon a compressed stent that has been loaded onto the balloon. The stent radially expands as the balloon is inflated thus forcing the stent into contact with the body lumen and forming a supporting relationship with the lumen walls. Alternatively, self expanding stents may be deployed with a sheath-based delivery catheter. Deployment is effected after the stent has been introduced percutaneously, transported transluminally, and positioned at a desired location by the delivery catheter. In addition to angioplasty and stenting procedures, other therapeutic procedures require the use of a delivery catheter; e.g. drug delivery devices, filters, occlusion devices, diagnostic devices, and radiation treatment.
Typically, the placement of such therapeutic delivery catheters involves the use of a guide wire that may be inserted into a patient's vasculature through the skin and advanced to the location of the treatment site. The delivery catheter, which has a lumen adapted to receive the guide wire, is then advanced over the guide wire. Alternatively, the guide wire and delivery catheter may be advanced together with the guide wire protruding from the distal end of the delivery catheter. In either case, the guide wire serves to guide the delivery catheter to the location to be treated.
There are four general types of catheters; i.e. Over The Wire (OTW) catheters, Multi-Exchange (MX) catheters of the type, for example, disclosed in U.S. Pat. No. 4,988,356 issued Jan. 29, 1991 and entitled “CATHETER AND GUIDE WIRE EXCHANGE SYSTEM” and U.S. Published Patent Application No. 2003/0191491A1 published Oct. 9, 2003 and entitled “CATHETER AND GUIDE WIRE EXCHANGE SYSTEM”; rapid exchange catheters, and fixed wire or a balloon on a wire catheters.
OTW and rapid exchange catheters require use of a guide wire separate from the catheter while a fixed wire or balloon on a wire catheter has an integral guide wire. An OTW catheter comprises a guide wire lumen that extends the entire length of the catheter. The guide wire extends through the catheter guide wire lumen, and the distal and proximal portions of the guide wire extend beyond the distal and proximal ends of the catheter respectively. An MX catheter has an over-the-wire configuration while the catheter is within a patient's body. Thus, the guide wire is disposed entirely within the catheter wire lumen except for the distal and proximal portions of the guide wire that extend beyond the distal and proximal ends of the catheter respectively when the catheter is fully inserted into the patient.
OTW and MX catheters have many advantages traceable to the presence of the full length guide wire lumen, such as sufficient stiffness and pushability for readily advancing the catheter through the torturous vasculature and across tight stenosis. The full-length guide wire lumen permits removal and replacement of the guide wire in an indwelling catheter, as may be required to alter the shape of the guide wire tip. It is also sometimes desirable to exchange one guide wire for another guide wire having a different stiffness. For example, a relatively soft or flexible guide wire may prove to be suitable for guiding a PTCA catheter through a particularly tortuous anatomy, whereas following up with a stent delivery catheter through the same vasculature region may require a guide wire that is relatively stiffer.
Traditional over-the-wire catheters do have some shortcomings, however. For example, it often becomes necessary, in the performance of a PCI, to exchange one indwelling catheter for another. In order to maintain a guide wire in position while withdrawing the catheter, the guide wire must be gripped at its proximal end to prevent it from being pulled out of the blood vessel with the catheter. For example, a PTCA catheter that may typically be in the order of 135 centimeters long is longer than the proximal portion of the standard guide wire that protrudes out of a patient. Therefore, exchanging an over-the-wire PTCA catheter requires an exchange guide wire of about 300 centimeters long, whereas a standard guide wire is approximately 175 centimeters long.
In one type of over-the-wire catheter exchange, the standard length guide wire is first removed from the lumen of the indwelling catheter. Then, a longer exchange guide wire is passed through the catheter to replace the original wire. While holding the exchange guide wire by its proximal end to control its position in the patient, the catheter is withdrawn proximally from the blood vessel over the exchange guide wire. After the first catheter has been removed, the next OTW catheter is threaded onto the proximal end of the exchange guide wire and is advanced along the exchange guide wire, through the guiding catheter and into the patient's blood vessel until the distal end of the catheter is at the desired location. The exchange guide wire may be left in place or it may be exchanged for a shorter, conventional length guide wire. In an alternative type of catheter exchange procedure, the length of the initial guide wire may be extended by way of a guide wire extension apparatus. Regardless of which exchange process is used, the very long exchange guide wire is awkward to handle, thus requiring at least two operators to perform the procedure.
A balloon catheter capable of both very fast exchange and simple guide wire and catheter exchange is particularly advantageous, and catheters designed to address these needs are sold by Medtronic Vascular of Santa Rosa, Calif. under the trademarks MULTI-EXCHANGE, ZIPPER MX, ZIPPER AND/OR MX. Such a catheter is shown and described in the above referenced U.S. Pat. No. 4,988,356 which is incorporated herein by reference in its entirety. An MX catheter includes the catheter shaft having a cut that extends longitudinally between the proximal end and the distal end of the catheter and extends radially from the catheter shaft outer surface to the guide wire lumen. A guide member coupled to the catheter shaft functions to temporarily open the cut such that the guide wire may extend transversly into or out of the cut at any location along its path. By moving the proximal shaft through the guide member, the effect of the over-the-wire length of the MX catheter is adjustable.
When using the MX catheter, the guide wire is maneuvered through the patient's vascular system such that the distal end of a guide wire is positioned across the treatment site. With the guide member positioned near the distal end of the catheter, the proximal end of the guide wire is threaded into the guide wire lumen opening at the distal end of the catheter and through the guide member such that the proximal end of the guide wire protrudes out the proximal end of the guide member. By securing the guide member and the proximal end of the guide wire in a fixed position, the catheter may then be delivered over the guide wire by advancing the catheter toward the guide member. In so doing, the catheter advances through the guide member such that the guide wire lumen envelopes the guide wire as the catheter is advanced in to the patient's vasculature. In a PTCA embodiment, the MX catheter may be advanced over the guide wire until the distal end of the catheter having the dilation balloon thereon if positioned within the stenosis and essentially the entire length of the guide wire is encompassed within the guide wire lumen. Furthermore, the indwelling MX catheter may be exchanged with another catheter by reversing the operation described above. To this end, the indwelling catheter may be removed by withdrawing the proximal end of the catheter from the patient while holding the proximal end of guide wire and the guide member in a fixed position. When the catheter has been withdrawn to the point where the distal end of the cut has reached the guide member, the distal portion of the catheter over the guide wire is of a sufficiently short length that the catheter may be drawn over the proximal end of the guide wire without releasing control of the guide wire or disturbing it's position within the patient. After the catheter has been removed, another MX catheter may be threaded onto the guide wire and advanced over the guide wire in the same manner described above with respect to the MX catheter. The MX catheter not only permits a catheter exchange without the use of a very long exchange guide wire and without requiring withdrawal of the initial placed guide wire, but it also overcomes many other difficulties discussed in association with rapid exchange catheters described below.
Rapid exchange catheters were developed in an attempt to eliminate the need of a guide wire extension or exchange wires. Catheters of this type are formed so that the guide wire is located outside of the catheter except for a short guide wire lumen that extends within only a comparatively short, distal segment of the catheter. The rapid exchange catheter's proximal exit port is typically located about 5 centimeters to 30 centimeters proximal to the catheter's distal end. In use, the guide wire is typically placed in the patient's vascular system. The distal segment of the rapid exchange catheter is then threaded onto the wire. The catheter can be advanced alongside the guide wire with its distal segment being attached to and guided along the guide wire. The rapid exchange catheter can be removed and exchanged for another rapid exchange catheter without the use of a very long exchange guide wire and without required withdrawal of the initially placed guide wire.
A difficulty associated with rapid exchange catheters is that it is not possible to exchange guide wires in an indwelling rapid exchange catheter, as can be done advantageously with OTW catheters. A guide wire can be withdrawn, sometimes unintentionally, from the proximal guide wire port, thus derailing an indwelling rapid exchange catheter. However, neither the first guide wire, nor the replacement guide wire, can be directed back into the catheters proximal guide wire port that is hidden remotely in the guiding catheter within the patient.
Guide wires are commonly back loaded into the delivery catheter. In this operation, the guide wire proximal end is inserted into the distal tip of the catheter. It is pushed through the catheter until it extends out of the proximal guide wire exit. In a traditional over-the-wire catheter, the proximal guide wire exit is in the proximal end of the catheter through its inflation luer. The rapid exchange proximal guide wire exit is the termination of the short guide wire tube a few centimeters (typically 25 centimeters) beyond the distal tip of the catheter. In the MX catheter, the proximal guide wire exits through the guide member position on the proximal shaft of the catheter. As an alternative to back loading a guide wire into the delivery system, a guide wire may also be front-loaded. In a front-loading operation, the distal tip of the guide wire is inserted into the guide wire lumen on the proximal shaft and pushed through until it exits the distal tip of the delivery catheter. A front-loading operation is possible with OTW and MX catheters if the guide wire will be exchanged during procedures. A front-loading operation is not used with a rapid exchange catheter since the guide wire cannot be exchanged while the catheter is inserted into the patient. With a rapid exchange catheter, the insertion of the distal tip into the proximal end of an indwelling catheter guide wire lumen is pure chance due to the fact that the proximal end is typically 125 centimeters from the exit location of the catheter from the patient at the femoral artery in the patient's groin.
Over-the-wire and rapid exchange catheters are commonly packaged and stored in a packaging hoop that consists of coiled tubing into which the catheter is inserted. A fitting located at the proximal end of the catheter is provided with a distal hub that fits into an opening in the tubing thus securing the catheter in the hoop. However, the guide member of an OTW/SW catheter may have a diameter greater than the diameter of the tubing used in the standard catheter hoop and, as a result, the guide member will not fit into the tubing opening and the distal hub will be unable to secure the catheter.
In an attempt to overcome this problem, a packaging component has been developed that may be secured to an open end of a coiled tube and is configured to receive the guide member therein. The packaging component comprises a tubular body having a passageway extending therethrough comprised of a first cavity and a second cavity. The first cavity is sized to receive the guide member therein, and the second cavity has at least one resilient arm projecting into the passageway. The resilient arm prevents movement of the guide member through the second cavity unless sufficient force is supplied to overcome the force of the resilient arm. A device of this type is shown and described in U.S. patent application Ser. No. 10/251,575 filed on Sep. 20, 2002 and assigned to the assignee of the present invention.
This packaging component has an opening therethrough which is generally tubular having a longitudinal axis, and the cross section of this opening is substantially circular. Thus, the fitting may be inserted into the packaging component along its longitudinal axis and at any angle of rotation with respect to the longitudinal access. That is, the fitting may be freely rotated within the packaging component or retainer about its longitudinal axis. This, however presents certain problems. For example, when an operator is loading a catheter into the hoop through the retainer, the fitting can be inserted into the retainer at any angle with respect to the periphery of the retainer (i.e. 360 degrees of freedom). Any rotation of the fitting with respect to the catheter shaft could result in a twisting of the catheter shaft resulting in a damaged catheter. Furthermore, an operator may couple the catheter fitting to an inflation device before removing the catheter from its packaging possibly causing unwanted twisting of the catheter and likewise resulting in catheter damage.
Accordingly, it would be desirable to provide an improved packaging assembly for an OTW/SW catheter which not only provides a relatively stable guide member traction force over time, but one that also prevents unwanted twisting of the catheter fitting with respect to the catheter shaft. Other desirable features and characteristics of the present invention will become apparent from the following detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.